A two-stage Long March 2C rocket, fueled by liquid hydrazine and nitrogen tetroxide propellants, boosted the Yaogan 30-04 satellite group into orbit approximately 370 miles above Earth on a track inclined at an angle of 35 degrees to the equator, according to data published by the U.S. military.

The Yaogan series of satellites are believed to be operated by the Chinese military for intelligence-gathering purposes.

Some analysts suggested the nine Yaogan 30-01, 30-02 and 30-03 satellites launched over the last three months could be testing new electronic eavesdropping equipment or helping the Chinese military track U.S. and other foreign naval deployments.

But details about the spacecraft and their missions have not been disclosed by the Chinese government.

China’s military has another satellite named Yaogan 30, but it is in polar orbit and believed to be a high-resolution imaging spacecraft.